The New Frontier

The use of lasers in dentistry has been growing ever since they were first introduced to the profession in 1989. Their applications, as well as the research available to support them, also continue to evolve. Currently, more than 20 indications for dental laser use have obtained United States Food and Drug Administration 510(k) clearance. From laser-assisted attachment procedures to wound healing to hard tissue applications, the use of dental lasers offers patients additional treatment options. Periodontist and laser expert Dr. Samuel B. Low shares his expertise on how dental lasers are best incorporated into dental and dental hygiene practice.

What are the typical uses for lasers in dentistry and dental hygiene practice?

The use of lasers in dentistry is dependent on the kind of tissue (hard or soft) that is being targeted. Various lasers have specific wavelengths that correspond to respective absorption curves of the target oral tissues (see sidebar).^1–5 The use of soft tissue lasers is indicated for periodontal therapy, surgical incision/excision of areas as frenectomies, canine exposure for orthodontics, and papiloma removal. Lasers are also utilized in the treatment of aphthous/herpetic lesions. Some protocols include laser-activated whitening and low-level light therapy to reduce inflammation.

Hard tissue laser indications often focus on managing root surfaces for calculus removal and detoxification, and altering bone levels for restorative crown lengthening. Lasers can be utilized to remove decay and create retentive preparations for respective restorative procedures.

What does the evidence show regarding the use of the dental laser as an adjunct to scaling and root planing?

The primary objective of scaling and root planing is to detoxify a tooth surface, thus reducing inflammation and encouraging a healthy periodontium that will result in tooth retention. Most studies comparing scaling and root planing alone to laser use in combination with periodontal debridement have compromised research designs that result in vague conclusions. Parameters studied include gingival and plaque indices, pocket depths and attachment levels, and quantity and quality of microorganisms. The period of study shows that the longer the investigator waits to gather end result data on laser utilization in scaling and root planing, the more inconclusive the results. This suggests that there are many variables that contribute to managing periodontal disease beyond a single therapeutic modality.^6–8

Is there long-term evidence to show that laser use, in conjunction with scaling and root planing, provides superior outcomes to debridement alone?

Several systematic reviews have been completed demonstrating minimal value of adding laser therapy to competent scaling and root planing, especially long-term (ie, 3 months or longer). Most studies utilize lasers as diodes that act on soft tissue as their targets, and these respective lasers have minimal positive impact on root surfaces for detoxification. Therefore, unless the study includes erbium lasers as the instrument on root surfaces and calculus, the only effect of a soft tissue laser is no change or a negative influence. Erbium lasers, however, do show positive changes in outcomes over time since they can detoxify root surfaces and remove calculus without thermal damage.⁹ Diode and Nd:YAG lasers are hemostatic as their respective wavelengths seek out the hemoglobin in the wound and coagulate the area. An advantage to their use during a scaling and root planing procedure is the visual access provided to the site by decreasing hemorrhage.

The therapeutic use of lasers is sometimes referred to as “disinfecting the pocket.” What does this mean?

There are multiple claims that lasers “disinfect” or “decontaminate” a pocket. And while studies are mixed as to a laser’s definitive effect on periodontal pathogens, few organisms can survive the thermal effect of most lasers. Some periodontal pathogens, such as Porphyromonas spp, are pigmented, thus the rationale for using diode and Nd:YAG lasers whose wavelengths and absorption are attracted to darker pigments.

Some in vivo and in vitro studies demonstrate a reduction of organisms with laser use over scaling and root planing alone. The timeframes of repopulation of the organisms vary, and generally show minimal changes after 30 days from prelaser baselines. This return of periodontal pathogens may be due to the host susceptibility and the anatomy of the pocket, especially in increased depths and furcation areas.

Photodynamic therapy (PDT) uses a lower wavelength diode laser to activate a dye placed in a sulcus. The theory is that the dye activation invades the cell walls of pathogenic microorganisms, rupturing cell membranes and releasing cytoplasm, resulting in cell death. Systematic studies are inconclusive as to whether the addition of PDT to scaling and root planing is a positive augmentation to conventional management.¹⁰

How effective are lasers at calculus removal?

Soft tissue lasers, such as diodes and Nd: YAG, cannot be used effectively on hard tissue surfaces, such as roots. With increased wattage, the root surface will become charred, eliminating the opportunity for tissue to attach to the surface. Subgingival calculus is generally pigmented, and the wavelengths of these respective lasers will seek out the pigment. The result is either the nonremoval of calculus or damage to the root surface due to the increased heat generated by the attraction to the pigment. Erbium lasers, however, do not have an affinity for pigment and create ablation in all tissues with minimal effects of heat. Their wavelength is attracted to hydroxyapatite surfaces and thus they are better able to detoxify a root surface. Several studies demonstrate their ability to remove calculus, their positive effect on the smear layer, and their ability to decrease root endotoxins.

Is the theory that laser use causes better healing and periodontal attachment when used in conjunction with scaling and root planing correct? If so, how does this occur?

The American Academy of Periodontology’s definition of scaling and root planing is using instrumentation to remove plaque (microorganisms), calculus, cementum or surface dentin, toxins, and stain from teeth. There is no mention of mechanical removal of soft tissue as de-epithelization or debriding the soft tissue wall, which would be defined as curettage. Histological studies clearly demonstrate that scaling and root planing reduces inflammation and encourages wound healing by a long junctional epithelial attachment, not periodontal “new” attachment.

A hypothesis in support of laser curettage suggests that enhanced wound healing could result from three possibilities: physical reduction of the pocket by degranulation of the internal pocket wall, biostimulation of fibroblasts, or reduction of inflammation by the physical removal of host defense cells. The advantage of a soft tissue laser used in scaling and root planing is confined only to decreasing hemorrhage at the time of the procedure, unless definitive curettage is incorporated into the procedure. As stated above, if detoxification of a root surface is required for reattachment, then the erbium laser would be the best choice.

Are there contraindications to laser use?

Lasers in dentistry are safe if the clinicians operating them are well educated and trained in their use. This results from engaging in continuous learning through university-based training or objective continuing education programs. However, laser dental therapy is a “new frontier” and still holds mysteries in both technique and results. When clinicians respect the laser as a device that requires an understanding of physics, and as a tool in the periodontal management armamentarium, they will be rewarded with success.

REFERENCES

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7. American Academy of Periodontology statement on the efficacy of lasers inthe non-surgical treatment of inflammatory periodontal disease. J Periodontol. 2011;82:513–514.
8. Sgolastra F, Petrucci A, Gatto R, Monaco A. Efficacy of Er:YAG laser in thetreatment of chronic periodontitis: systematic review and meta-analysis. Lasers Med Sci. 2012;27:661–673.
9. Renvert S, Roos-Jansåker AM, Claffey N. Non-surgical treatment of periimplantmucositis and peri-implantitis: a literature review. J Clin Periodontol. 2008;35(Suppl):305–315.
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From Dimensions of Dental Hygiene. May 2013; 11(5): 38–41.